I'm usually a 52/L. I almost always take 6 in SS. 5 worked better for me on Clover, but that's the only piece I remember wanting to size down on. I don't have the Moonless cardigan, but I would guess 6 for myself and, by extension, you.

It really depends on you. People vary in their tolerance for extreme temperatures. But I would be really surprised if you couldn't find a better solution among the already-given suggestions. What's your warmest overcoat right now? If it's some Banana Republic-type topcoat, then your first job is to get yourself a legit overcoat. If that (plus the scarf and gloves thing) doesn't get you comfortable, then look into the other options.

Personally never found this to be a problem since when I'm going to/from work I'm moving around, while when I'm at work, I'm mostly seated or at least not moving around as much. I'm still warmer when inside than outside, but not so much that I'm sweating in the first case or shivering in the second.

Top coats are by definition not that warm. Most coats on the market today are fairly scrawny...maybe 18oz, often less than that. But you can still find overcoats that are truly heavy. For instance I would guess this British Warm at O'Tradnell's is plenty heavy:http://www.oconnellsclothing.com/product.php?productid=18507&cat=263&page=4

I am not a fran. Does not go with a suit at all.Better alternatives:1) scarf + gloves + suit + overcoat and I'm ready for about anything. Try getting a heftier scarf and/or gloves before giving up and wearing something down-filled.2) add a waistcoat for extra warmth. either as a part of a 3 pc suit or something knitted if you want a little more casual and/or something that can be bought to a 2 pc suit you already own3) Have at least one real cold weather suit. Like at...